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Excercise 14.13 question d

Posted: Tue Feb 07, 2017 7:50 pm
by Jinghui Song 2J
Write the half-reactions, the balanced equation for the cell reaction, and the cell diagram for each of the following skeletal equations:
d. Au+(aq)--- Au(s)+Au3+(aq)
in this reaction, the oxidation half equation should be Au+(aq)---Au3+(aq)+2e-, but the answer on the back of the book gives Au(aq)---Au3+(aq)+3e-

Also, why is the cell diagram given as Au(s)/Au3+(aq)//Au+(aq)/Au(s)? I think on the left it should be like Pt(s)/Au+(aq), Au3+(aq)

Can anyone help answer my question? Thank you in advance!

Re: Excercise 14.13 question d

Posted: Tue Feb 07, 2017 9:52 pm
by stephanieyang_3F
Hi! My understanding is that you derive your half-reactions that are listed in the Appendix. The Appendix lists Au+ +1e- ---> Au and Au^3+ + 3e- -----> Au. Naturally you'd want to set up the balanced redox half reactions giving you Au+ -> Au3+ + 2e- for your oxidation reaction and Au+ + 1e- -> Au for your reduction reaction but since there are not standard potentials that exist for Au+ -> Au3+ + 2e-, you just have to manipulate the half reactions listed on the Appendix to give you the base reaction they give you in the problem.

Remember you base your cell diagram on your oxidation and reduction half reactions, so the LHS would be your anode (oxidation rxn) and your RHS would be your cathode (reduction reaction). You might've thought of it that way because you wanted to use Au+ -> Au3+ + 2e- for your oxidation reaction. Hope I helped.